Magnetic shunt for dynamo-electric machines



Aug. 14, 1928.

Filed April 2, 1926 l/VVEN 70/2 2516.49

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In v

Patented Aug it, 192%,

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ROBERT G. DEALE, 0F PLAINFI'ELD, NEW JERSEY, ASSIGNUR T0NILIES-BEMENT-IPONJD' COMPANY, OF NEW YORK, N. Y.,

A. CORPORATION 035 NEW JERSEY.

v MAGNETIC SHUNT FUR JDYNAMU-ELEGTRIG BEACHENES.

Application (filed April 2, 19%. Serial No. 993%.

This invention relates to generators, and particularly to a generatoradapted to operate with its armature circuit constantly and 7 directlyconnected to the armature circuit of a motor.

' An object of the present invention is to provide improved magneticcircuits including a restricted magnetic path tor the residual flux of agenerator so that a shunt path oi limited cross section and permeahiiityis available for the said residuai magnetic flux from one magnetic poleto another without passing through the armature,

Another object of importance is that the shunt provided for thismagnetic flux due to the residuai magnetism is fixed and is formedbyinserts, preieraloiy in the form of flenihie sheem of magnetic materialdisposed between and irictionaliy engaging adjacent pole pieces ofopposite poiarity @ne feature which is advantageous therefore is that apoie piece together its winding, may he removed torepair or replace thewinding with a minimum of dificui'ty and with the assurance that theshunt is again in position and operative when the poie piece is repiacedAnother feature which is advantageous is the fiexihie sheets forming themagnetic shunt may he attached to the tips of the interpoi'es and heidin piece by the retaining means for interpoie or driving many equipmentsich i s0 s hoists, machine to i e to have individt eparateiy ature c csre a as he motor s q n "I! or electricity e tor is reversed by a switchefiecting a reversal of the shunt field circuit of the generator. Thisswitch, in the above mentioned patent, is moved from one operativeposition to the other by dogs on the reciprocating planer tabie. Withthe switch in its mid or neutral position and the generator field openresidual magnetism in the pole pieces of the enerator may he and irequently is sufficiently strong to causea volt age to be generatedsuficient to siowiy re tate the planer motor and thus cause a steep-,ing movement of the planer table. are

vent the residual magnetism of the tor shown in the patent from caucreeping action when its field circuit a momentary current is passedthro n the generator fieid circuit in the reverse direc tion Thiseiiminates or materi y r d the magnetization of the generator soprevents any voltage heing This manner of eliminating the streets oiresiduai magnetism is not whoiiy satisfao tory' as the demagnetizingcurrent "nay he too weai or too strong, or maintained for too iong ortoo short a It aiso re quires speciai switch contacts tor its circuitwhici; mechanism,

Appiicant has there construction to T magnetism enter compiicationsresumed ore devised pres- I f I) the sheets or at requiring the circuitsor adgust 'l these otherohjects in nhodied Figure 1 is a transverse viewof a genera- ,tor provided with the magnetic shunt forming the presentinvention.

Fig. 2 is an enlarged view of'a portion of a generator showing themagnetic shunt more clearly, and

Fig. 3 is an isometric view of a shunt attached to its interpole.

In the above mentioned drawing I have shown but one embodiment of theinvention v enclosing the armature therewithin.

' Referring more in detail to the figures of the drawing, I show agenerator having a frame 10 to which are attached pole'pieces 11 onwhich are mounted shunt field windings 12. Between the pole pieces 11are the interpoles 13 on which are small series field thought to benecessary.

windmgs indicateddiagrammatically at 14. On the inner free ends of thelnterpoles 13 are the cross bars 15. Within the pole pieces 11 and 13 anarmature 16 is adapted to rotate. As all of the-above mentioned partsare, or may be, of well-known and standard construction, furtherdescription is not As will be seen, the tips of the pole pieces 11 areextended laterally and are adapted to engage the sheets or laminationsof magnetic material 17 forming the magnetic I shunt path for theresidual flux between adurpose' the jacent pole pieces 11. For thissheets of magnetic material 17 w 10h may be of a material such as ironor steel, and preferably flexible, are inserted within the space betweenand engage adjacent pole pieces of the generator. Preferably two or morelaminations 17 are provided frictionally and resiliently held againstthe end surfaces of the polepieces and held in place by means of screws18 attached to the bars 15 on the inner ends of the interpoles 13. Theselaminations therefore press resiliently against the tips of the polepieces 11. These shunt pieces also closely surround the generatorarmature 16 and provide a permanently closed magnetic path between theadjacent pole piec'esof the generator without the flux being required topass through the armature 16. The shunt pieces 17 are preferably made ofsuflicient width to extend throughout the width of the pole pieces 11and the coils of the armature 16.

Thearea in cross section of the shunt pieces is limited so that they aresubstanat their mid tially saturated by the flux due to the residualflux in the pole pieces 11. This, in the circuits for a planer operatingsystem, has been found to be equal to approximately one to two per centof the cross sectional area of the pole pieces 11. Under normaloperation of the planer the amount of flux passing through this shuntpath is relativelysmall on account of the limited cross section andpermeability of the laminations 17, and is therefore not sufficient toadversely eflect the operating efliciency of the system.

As the sheets 17 of magnetic material forming the shunts are attached tothe interpoles '13, any flux set up by their series winding is shuntedaway from the armature.

What I claim is:

1. The combination witha dynamoelectric machine of a magnetic shuntcomprising a flexible sheet of magnetic material having limitedpermeability positioned between and adapted to resiliently butpermanently engage magnetic pole pieces 0 opposite polarity whereby fluxdue to residual magnetism may be shunted around the armature of saidelectric machine.

2. The combination with a dynamoelectric machine ofa magnetic shuntcomprising a plurality of superposed sheets of magnetic materialpositioned between and ada ted to resilientlybut permanently engage aacent pole pieces whereby flux due to residual magnetism may be shuntedaround the armature of said electric machine. 1

3. The combination with a dynamoelectri machine of a magnetic shuntcomprising a pluralit of superposed sheets of magnetic materia extendingsubstantially throughout the width of the pole pieces ositioned be tweenand adapted to. resiliently but permanently engage adjacent pole pieceswhereby flux due to residual magnetism may be shunted aroundthe-armature of said electric machine.

4. The combination with a dynamoelectric machine having aplurality'ofpairs of magnetic pole pieces and interpoles between adj acent polepieces, of a magnetic shunt comprising sheets of magnetic materialpositioned between and adapted to engage adjacent pole pieces, saidsheets being attached ortions to said interpoles.

5. The com ination with a dynamoelectric machine of a magnetic shuntcomprisin magnetic material of limited cross sectiona area positionedbetween and adapted to engage magnetiopole pieces of opposite polarity,the cross sectional area and permeability rial being such that it issubstantially saturated by the flux due to residual magnetism in saidpole pieces, said material being at tached at its mid portions to saidinterpolesi 7. The combination with a dynamoelectrie machine of amagnetic shunt comprising magnetic material having limited permeabilitypositioned between and adapted to engage magnetic pole pieces ofopposite polarity,interpoies having series windings there- 'on, andmeans to attach said shunt to said interpoles, whereby flux due toresidual magnetism in said pole pieces and said series windings on saidinterpoles may be shunted around the armature of said electric machine.

In testimony whereof, 1 hereto afix my 20 signature.

ROBERT C. DEALE.

